Process and apparatus for the production of metallic dust



R. B. FINN.

PROCESS AND APPARATUS FOR THE PRODUCTION OF METALLIC DUST.

APPLICATION men Aue.14. 1919.

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ROBERT B. FINN, OF MILL VALLEY, CALIFORNIA.

Application filed August 14, 1919.

To all whom it may concern Be it known that I ROBERT B. FINN, a citizen of the United tates, and a' resident of Mill Valley, Marin County, California, have invented new and useful Improvements in Processes and Apparatus for the Production of Metallic Dust, of which the followingais a specification.

y invention has for its principal object the condensation of metallic vapors in very minute particles, free from contamination of oxides or other impurities, and is particularly applicable to the production of so called zinc dust.

This I accomplish by vaporizing the metal in a retort by heat, the said retort being closed from the atmosphere, but having a communication into a relatively large condensing compartment. The retort is provided with suitable heating means as for example being enclosed in a furnace of usual construction and a connecting neck or thimble is preferably attached around the neck of the crucible o-r retort and opening 1n to the said condensing chamber. I prefer to form the chamber cylindrical, and with a tapering or funnel shaped bottom, having suitable valved or closure means, which may be opened to abstract the metal dust which condenses within the chamber. I also form the chamber with an upwardly extendin conical top; and provide a flanged or valve handhold opening for inserting and operating tools to reach and clean the crucible neck and connecting tube to the condenser of con-' densed accretions.

The connecting tube or thimble I direct upwardly, sothat any condensed particles or accretions thereon, upon being loosened, from any cause, will tend tofall into the retort or crucible. The tube or thimble connecting the crucible neck with the cylindrical condensing chamber, preferably enters the connecting chamber on its side somewhat below its center, the chamber standing with its cylindrical axis substantially vertical. I am aware that the use of retorts and condensing chambers generally is old, but by my process and apparatus, I am enabled to secure a finer grade of product,'having superior advantages in the commercial adaptation in which the metallic dust may be used.

In the accompanying drawings Fig. 1 is a vertical cross section through the furnace retort and thimble, and conical top and bottom.

Serial No. 317,603.

Fig. 2 is a view at right angles to Fig. '1 showing in detail the arrangement of the flanged or valved opening.

F 3 is a section in plan of Fig. 1 on the line I,'of Fig. 3.

Throughout the fi res the same numerals refer to the identica parts. i

The rear wall of the furnace is indicated at 1, having suitable vent means as 2, and a combustion chamber as 3, supplied with suitable heatin means as fuel oil through the nozzle 4. lIrranged within said furnace is the retort shelf 5, and the front wall 6. Mounted within the said furnace and exposed to the heat is the retort 7 within which is to be placed the metal, 8, from which the metallic vapor to form the dust is to be produced.

The retort is preferably formed with a neck as at 9, which is closed about by the wall '6 in any suitable manner and projects therethrough and into the thimble 10.

.I prefer to lute, as at 11, the neck of the thimble and the mouth of the retort, although closure may be effected in other ways. The thimble projects into the condensing chamber through the wall 12.

The walls as 12, 13, and top 14 and the bottom 15 I prefer to form of thin metal that it may readily dissipate heat. The condensing chamber I prefer .to make in cylindrical form, the axis of which cylinder is substantially vertical. The top of the cylinder I form conically with the apex of the cone .at the highest point, and the bottom of the cylinder of conical shape with the outlet at the lowest point, as indicated at 16. This latter is preferably closed by a gate, or any suitable means, as the plate 17.

Opposite to the retort mouth and the thimble 10, I provide an opening 18, and closure m'eans therefor as the wedge shaped disk 19,

actuated by the handle 20, which closes tightly the opening 18, by wedging with the lug 21. Other forms of gate may be used in place of the flat plate 17, if desired.

The entire chamber I'mount on rollers as 22, 23 so that it may be moved across the floor 24 so that the thimble 10 is removed from the neck 9 of the retort 7 giving ready access to the retort and wall 6, which latter wall is removed from time to time as may be necessary in the retort operations .of cleaning, charging, etc.

In practice the retort 7 may be made of graphite and charged to 1,000 pounds, or

thimble 10 is also preferably to be upward,

and the size of the opening through the thimble 10 is to be larger than the neck 9 of the retort 7 so that although it is set at an angle, its projecting edge will clear the upward projecting neck 9, as the complete chamber and the thimble are moved across the floor 24 on rollers 22, 23.

After the retort is chargedand the'heatcommenced the chamber is moved back 'into place with the retort neck 9 projecting within the thimble 10, as shown in Fig. 1,and the clay luting 11, is aflixed to seal the clearance space around the thimble and retort neck to prevent the ingress of air or gases. 1

The rollers 22, 23 are connected to "the chamber through a suitable supporting structure 25. The metallic vapors emerging from the neck 9 of the retort 7 under the action of heat from the chamber 3 passes through the thimble 10 and into the cooling chamber, within which condensation takes place.

The symmetrical form of the chamber, in horizontal cross section,'combined with the conical shaped top, prevents the formation of eddy currents within the chamber and consequently a slow condensation in most minute articles of metallic dust results.

The chamber is sealed from air contamination after the oxygen of its originally con tained air has been burned out by oxidation of the metallic vapor, or otherwise, so that the chamber contains a body of nitrogen in a perfectly still, or static, state. Into this body of static nitrogen the vapors slowly emerge from thimble 10, and as they emerge, as in the direction of the arrows-27, 28, 29, the particles are condensed and fall into the conical bottom 15, as indicated by the arrows 30. The dust so produced will be of a perfectly regular quality. Any deposit upon the walls of the thimble 10 will fall on to the thimble floor 31, and be prevented from contaminatin the dust collecting in the bottom 15. Sue accretions and condensations as occur within the thimble 10 and neck or mouth 9 may, from time to time, be;

the thimble engages with the neck of the re-' tort and is secured thereto with a joint, which may readily be accomplished by lut ing as with clay. The metal is now vaporized by the application of sufficient heat within the retort, by the furnace. The fumes or vapors from the retort will now the start of the process will be vaporized metallic zinc, which combined with the oxy gen of the air contained therein forms (1n the example here set out) zinc oxide. This zinc oxide will condense and fall in the form of a fine white powder or flakes, and is to be withdrawn from the outlet at the bottom of the funneled bottom portion of the condenser. closed and there will be remaining in the condenser a volume of substantially pure nitrogen and metallic vapor. The further condensation of the charge, of which there will be remaining in the neighborhood of 98%, will thereafter be condensed at the same rate as the metallic zinc is vaporized and such condensation will take place as zinc dust, in a fine pure metallic powder, free from oxide.

It is to be especially noted that in the construction of the condenser, theconical top is an essential element for the purpose of re-- tion mentioned above, the particles of zincoxide being condensed on the interior surface of covers of certain other shapes, as for example a flatplate, have been found to adhere thereto, until later portions of the condensation operation and are therefore not removable in the preliminary step of oxide abstraction, but become loosened and will fall into the zinc dust and-contaminate it.

It will thus be seen that I seek to prevent the condensation of the vapors until they arrive within the condensation chamber, and when they arrive therein, to bring about their condensation with the least amount of movement of the particles, so that the dustmay as nearly as possible fall through the chamber from their condensation within the body of static, or non moving, nitrogen gas.

I claim 1. A process for producing metallic dust consisting of vaporizing the metal in a retort by the application of heat, conveying the vapor to and condensing it within a sub stantially static body of nitrogen.

2. The process of manufacturing zinc dust which consists in vaporizing the zinc and then carrying the vapors into a closed cham This outlet is then immediately ber containing air, then exhausting the oxygen of the air from said chamber by conversion into zinc oxide (and then drawing off the zinc oxide) and then depositing zinc dust through the remaining atmospheric nitrogen.

3. A condensing chamber for metallic vapor, consisting of a cylindrical casing having an upward extending closed conlcal top and a downward extending conical bottom,

' an outlet spout from the said conical bottom and valve means for said spout.

4. A condensing chamber for metallic vapors, of cylindrical form, the axis of which cylindrical form is substantially vertical; a conical top to said chamber and a conlcal bottom to said chamber, means for admitting metallic vapors thereto, outlet means in said bottom and means for closing said outlet.

5. A condensing chamber for metallic vapors, of cylindrical form; a conical top and a conical bottom to said chamber, means for admitting metallic vapors thereto, an outlet in said bottom and a device for closing said outlet and an opening in the chamber wall and means for closing said outlet.

6. A condensing chamber for metallic vapors, of cylindrical form; the axis of which cylindrical form is substantially vertical; a

conical top to said chamber and a conical bottom to said chamber, means for admitting metallic vapors thereto, outlet means in said bottom and means for closing said outlet; in combination with a retort containing the metal to be'vaporized, said retort having a neck over which a thimble is luted.

7. A condensing chamber for metallic va pors, of cylindrical form, the axis of which cylindrical form is substantially vertical, a conical top to said chamber and a conical bottom to said chamber, means for admitting metallic vapors thereto, outlet means in said bottom and means for closing said outlet, an opening in the chamber substantially opposite the vapor inlet and closure means for said opening.

8. A condensingchamber for metallic vapors, of cylindrical form, the axis of which cylindricalform is substantially vertical; a conical top to said chamber and-a conical bottom to said chamber;.outlet means in said bottom and means for closing said outlet;

means for admitting metallic vapors to the said chamber and consisting of a thimble affixed to the chamber wall, and means constructed and adapted to supply said vapors through said thimble.

9. 'A process for producing zinc dust consisting of vaporizing the metal in a retort by the application of heat, conveying the vapor to and condensing it within a substantially static body of nitrogen.

10. A condenser comprising a vapor condensing chamber having Walls through which heat is emitted; a thimble forming a tight oint with said chamber and projecting from the side thereof, said thimble being through which the vapor is adapted to be in-. troduced into the chamber, an outlet for the condensate in the bottom of the chamber and closure means for said outlet.

11. A condensing chamber for metallic vapors, of cylindrical form, the axis of which cylindrical form is substantially vertical; a conical top to said chamber and a conical bottom to said chamber, means for admitting metallic vapors thereto, consisting of a thimble constructed and adapted to be afiixed to means supplying said vapors, and means supplying said vapors, sald chamber constructed with transfer means whereby it may be moved laterally to and from the said retort to facilitate access thereto, outlet means in said bottomand means for closing said outlet.

12. A condensing chamber for metallic vapors, of cylindrical form the axis of which cylindrical form is substantially vertical; a conical top to said chamber and a conical bottom to said chamber, means for admitting metallic vapors thereto, disposed in the cylindrical chamber wall, in combination with a retort containing the metal to be vaporized, said retort having a neck over which the said thimble is disposed and is luted thereto, said retort and thimble directed upward towards the chamber, outlet means in paid bottom and means for closing said out- 13. A condensing chamber for metallic vapors, of cylindrical form, the axis of which cylindrical form is substantially vertical; a conical top to said chamber and a conical bottom to said chamber, means for admitting metallic vapors thereto, consisting of a thim ble constructed and adapted to be affixed to means supplying said vapors, and means supplying said vapors, said chamber constructed with transfer means whereby it may be moved laterally to and from the said retort to facilitate access thereto, said retort and thimble directed upward towards the chamber, outlet means in said bottom and means for closing said outlet.

In testimony whereof, I have hereunto set my hand at Willits, California,

this 7th day of August, 1919. 

